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Tuesday, November 06, 2012

Spade-toothed whale Mesoplodon traversii Opape

The discovery of a pair of extremely rare Spade-toothed whales has been published in the journal Current Biology. I was there when they were exhumed (pics below) after being buried in the sand dunes of Opape beach (east of Opotiki) for just under a year and it all looks relatively clean, but the stench from the rotting flesh was unforgettably pungent. 
No-one suspected how rare the whales would be when they stranded. As normal procedure the DoC ranger took a DNA sample and sent it to Te Papa. In the meantime the whales were buried and then we subsequently had to deal with the mystery and drama of finding all the parts. That's why it looks like we dug up half the beach in the end - and we still couldn't find it all.
The guy at the bottom of the pit to the left is the actual landowner - he only discovered what was going on when he walked down to the end of his block to investigate what all the people and machinery were doing! It was a massive trench in the end. Problem is even with local knowledge and DoC's GPS point the tides, currents and storms move things around. We don't know why the whales stranded either or why they stranded where they did. 
The unfortunate thing was the distinctive spade tooth occurs only with males and so we never got to see it (being female and her calf). These whales are freakishly elusive and we are lucky to have had them identified. However I doubt very much can be gleaned about their diet, movement and so on from the fleshless bones alone.

Eureka! A proud Dr Anton Van Helden holds up the genitalia.

The Te Papa crew - and DoC - were hosted by the Hapu and through negotiations on the marae undertakings were made for the bones to be sent to Te Papa and for a management agreement to be made. Most important in this decision was Anton's passion for beaked whales and the assurance that Te Papa had the best facilities.  I saw a recent picture of the specimens in Wellington and they have been cleaned and capable of display by the looks of it. As long as they can get rid of that smell...
Two whales which died after becoming stranded in the Bay of Plenty were spade-toothed beaked whales, a rare species.
The female whale and male calf died on Opape Beach on New Year's Eve in 2010 and photos and tissue samples were taken.
Details of a study of the samples have been published in Current Biology by scientists from The University of Auckland.
Until now, the only evidence for the existence of Mesoplodon traversii came from three skull and jaw fragments found around New Zealand and Robinson Crusoe Island near Chile.
Dr Rochelle Constantine told Morning Report the whales were buried, but iwi allowed the carcasses to be exhumed and they are now at Te Papa Museum in Wellington.

"This is the first time a spade-toothed beaked whale has been seen as a complete specimen, and we were lucky enough to find two of them," lead scientist Dr Rochelle Constantine said.
"It's incredible to think that, until recently, such a large animal was concealed in the South Pacific Ocean and shows how little we know about ocean biodiversity."
Their findings have been published today in Current Biology.
Since the two animals are the only intact members of their species sighted, the spade-toothed beaked whale is the world's rarest whale. Until now the only evidence for the species' existence came from three skull and jaw fragments found around New Zealand and Robinson Crusoe Island, Chile.
On December 31, 2010, a 5.3 metre-long female whale and a 3.5 metre-long male calf stranded and later died on Opape Beach in the Bay of Plenty. After death they were measured, photographed and tissue samples were taken by the Department of Conservation.
The animals were initially misidentified as Gray's beaked whales, the most common beaked whale to strand in New Zealand. However subsequent genetic analysis at the University of Auckland revealed that they were spade-toothed beaked whales.
Following genetic identification the skeletal remains were exhumed, with the permission of Whakatohea Iwi Maori Trust and the Ngai Tama Haua hapu, and taken to the Museum of New Zealand Te Papa Tongarewa.

[...] says Dr Constantine.
"This is a real New Zealand story – it’s all linked here, from the discovery of two of the bone fragments to the identification of the species and now the first sighting of the whales."
She says it's not known why the whales have proved to be so elusive. The skull and jaw fragments analysed in 2002 were discovered in the 1950s, and the only other specimen known to exist is part of a skull found in Chile in 1986.
"It may be that they are simply an offshore species that lives and dies in the deep ocean waters and only rarely wash ashore. New Zealand is surrounded by massive oceans. There is a lot of marine life that remains unknown to us."

The unexplained arrival and death of these two whales reminds me of another incident in the area involving a pair of sea creatures some time ago. The name Opotiki comes from a local Maori story about Tarawa (a tipuna of the Whakatohea Iwi) who arrived mysteriously and brang with him two fish from his homeland that he released into a spring along the Waiotahi beach. This was called Opotiki-mai-tawhiti: the pet fish from afar.


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